For the treatment and prognosis of IH, the British Endocrine Society
[12], the Chinese Endocrinology Society
[15] and the Chinese Anti-Cancer Association Tumor Endocrinology Professional Committee
[16] all recommended that the severity of IH should be graded by CTCAE, according to the clinical manifestations of patients. Meanwhile, laboratory tests, such as anterior pituitary hormones, blood electrolytes, blood osmolality, urine osmolality and urine specific gravity, are necessary.
For IH patients assessed as CTCAE Grade 1 (mild fatigue, anorexia or mood changes without headache or asymptomatic), the ESMO and Chinese expert consensus suggests that ICI treatment can be continued. At the same time, according to the results of laboratory evaluation, the corresponding hormone replacement therapy should be performed for the damaged pituitary-target gland axis
[16][47]. For CTCAE Grade 2 IH patients (headache without visual disturbance), ESMO recommends that ICI therapy should be suspended, and prednisone at 0.5–1 mg/kg/d should be administered orally
[47]. If the patient’s symptoms do not relieve within 48 h, intravenous methylprednisolone at 0.5–1 mg/kg/d should be given, and the dose of prednisone should be reduced to 5 mg/d oral maintenance therapy within 2–4 weeks
[47]. The damaged pituitary-target gland axis should be treated with corresponding hormone replacement therapy. Since discontinuation of ICIs does not affect the natural history of hypophysitis
[48], and the survival benefit of continuation of ICI treatment of tumors is far greater than the risk of anterior pituitary dysfunction, ESMO recommends that patients with IH continue to use ICIs after the acute phase
[47]. The expert consensus of the Chinese Cancer Society
[15][16] proposed that ICI treatment should not be interrupted for CTCAE Grade 2 IH.For patients with IH in CTCAE grades 3-4 (severe mass effect: or severe headache, visual disturbance; or severe adrenal insufficiency: or hypotension, severe electrolyte disturbance), all guidelines recommend suspending ICI therapy
[1] and immediately Intravenous methylprednisolone 1 mg/kg/d, and glucocorticoids were reduced to prednisone 5 mg/d oral maintenance therapy within 2-4 weeks. At the same time, according to the test results, other damaged pituitary-target gland axes were given corresponding hormone replacement therapy. Until the acute phase of IH is relieved, ICI treatment is continued
[2]. For patients with ACTH and TSH deficiency, the Japan Endocrine Society
[3]recommends that low-dose levothyroxine (12.5-25 µg/d) be administered after hydrocortisone (10-20 mg/d) for 5-7 d and adjust the levothyroxine dose according to the serum level of FT4 to avoid inducing iatrogenic adrenal crisis. Studies have found that receiving high-dose (average daily prednisone dose greater than 7.5 mg) glucocorticoid therapy will affect the clinical antitumor efficacy of ICIs, reduce the overall survival rate of patients
[4], and increase the risk of infection, hyperglycemia, etc.
[5] and cannot significantly improve the prognosis of anterior pituitary dysfunction
[6]. In summary, high-dose glucocorticoid therapy is not recommended
[3],[7]. However, for patients with intractable headache and/or visual impairment, the Japanese Endocrine Society recommends the use of prednisone 0.5-1.0 mg/kg/d
[3]. Once symptoms such as intractable headaches and/or visual disturbances resolve, glucocorticoids should be rapidly reduced to physiologic replacement doses within 2–4 weeks
[8]. Since HPG axis damage is easier to recover and poses a lower threat to the survival of patients, the French Endocrine Association
[9] suggested that patients with HPG axis damage should be followed up for three months. If the HPG axis has not recovered after three months, the corresponding sex hormone replacement therapy can be given according to the patient's age and other circumstances. For patients with an impaired GH/IGF-1 axis, the French Society of Endocrinology does not recommend GH replacement therapy due to the background of the patient's primary malignancy
[10]. If the posterior pituitary is damaged and diabetes insipidus occurs, the Chinese Society of Endocrinology recommends the use of synthetic antidiuretic hormone (ADH) for treatment
[7].
Compared with other irAEs, the prognosis of IH is relatively good. Generally, after the acute phase of the disease, the treatment of ICIs can be resumed. Permanent HPA axis damage occurs in 86–100% of IH patients, requiring long-term glucocorticoid replacement therapy
[49]. Permanent HPA axis damage in PD-1/PD-L1 inhibitor-related IH is more common
[41]. Today, with the increasing use of PD-1/PD-L1, it is especially necessary to attract the attention of clinicians. In addition, studies have shown that the HPT axis often recovers at approximately 10.5 weeks, and the HPG axis can recover at approximately 25 weeks
[48].